With increasing environmental awareness, ink systems play an important role for a more ecological film-based packaging product. Marketing campaigns praise water-based inks as the green solution for a more sustainable product, but they leave out some important facts. A comparison of different ink systems on the market presents an interesting result.
The watery landscape
We all want water. We all want to use those products that benefit us and the world. It’s for our own good. Modern water-based ink systems have been around for at least the past 30 years, and in theory one would think that being water-based would equate well to being “ecofriendly” or “not harmful to the environment”. Read the full article in our eDossier “The true environmental impact of ink systems.”
Being kind to the environment generally means that these products contribute to green living or they help conserve resources like water and energy. The other facet is that eco-friendly inks should limit or prevent contributions to air, water and land pollution, keeping both the environment and human safety in mind.
Historically water-based inks were developed to eliminate harmful solvents like xylene and toluene, and to a lesser extent solvents like alcohols and esters. But right from the beginning it was clear that for the formulator, this was going to be a challenge. Thirty years ago, gravure metallic inks contained aromatic hydrocarbons as these nonpolar solvents lent themselves well to producing very bright metallic finishes.
Replacing toluene with water was unacceptable by any standards. The other challenge was that there were few water-borne resins or emulsions on the market and even fewer that were able to produce stable, good flowing ink systems.
If we compare the old and the new ink formulations, much has changed, and a lot has stayed the same. The similarities are that both sets of formulations utilise essentially the same kinds of raw materials – acrylic emulsions, waxes, solvents, surfactants, and pigment dispersions.
All of these products are synthetic, man-made raw materials, and the basic components are derived from petro-chemical sources. The only differences come from the technologies that are used to make the individual ingredients, but ultimately we’re still having to use synthetic and largely non-bio-based, non-biodegradable raw materials.
The problem with water
While water is a desirable, naturally occurring substance that is indisputably the most eco-friendly product there is, when it comes to printing ink, water is a problem. First of all, water has a high surface tension (72.8 dynes/cm) compared to 22.3 dynes/cm for ethyl alcohol, and this means that in order to “wet” most substrates, surface tension has to be reduced considerably if we are to achieve good print quality and a smooth laydown of the ink.
The only way to reduce than surface tension is to add either a surfactant or a solvent. So for water to be of any use to us, we’re going to have to “contaminate” it with a man-made solvent, and depending on the substrate being printed, the type of printing press and the desired printing speed, the amount of solvent can range anywhere from 2-20% of the press-ready ink. Learn more about the “The true environmental impact of ink systems” – you can easily download it for in our shop.